Recently, the kinds and the number of electric equipments of a vehicle are increasing rapidly, and the consumption of the vehicle battery is becoming rapidly. Therefore, a value of electric current flowing through a wire harness connected to the battery is measured by a current detecting device, and on the basis of the measured data, the degree of consumption of the battery is grasped.
As a conventional current detecting device used for such the purpose, a device described in, for example, PTL 1 has been known. FIG. 9 is an exploded perspective view of a current detecting device described in PTL 1, and FIG. 10 is a sectional view of a main portion thereof.
As shown in FIG. 9, this current detecting device 210 includes a busbar 230, a magneto-electric converting element 250, a housing 220 and a shield plate 260. An electric current flows through the busbar 230. The magneto-electric converting element 250 is arranged close to the busbar 230, and outputs an electric signal in response to a magnetic field generated by the current flowing through the busbar 230. The housing 220 is made of nonmagnetic resin, and accommodates the magneto-electric converting element 250 and a part 231 of the busbar opposing to the magneto-electric converting element 250 with a constant relation. The shield plate 260 for magnetic shield is attached to a main body portion 226 of the housing 220 so as to surround the magneto-electric converting element 250 and a part 231 of the busbar which are accommodated and held in the main body portion 226 of the housing 220.
A part 231 of the busbar 230, as shown in FIG. 10, is accommodated inside an accommodating hole 226A formed on a one-side face of the main body portion 226 of the housing 220. Further, the magneto-electric converting element 250 is mounted on a circuit board 251, and the circuit board 251 is accommodated inside an accommodating hole 226B formed on the other-side face of the main body portion 226 of the housing 220.
Further, as shown in FIGS. 9 and 10, the shield plate 260 includes a pair of side plates 261 and a connecting plate which connects base ends of the both side plates 261 to each other, and is formed in section in the U-shape in which an opening portion 265 is formed between leading ends of the both side plates 261. The shield plate 260 is fitted to the outside of the main body portion 226 of the housing 220 from the leading end side of the opening portion 265. A claw portion 263 at the leading end of the side plate 261 of the shield plate 260 engages with the housing main body portion 226, whereby the shield plate 260 is fixed to the housing 220.